Abstract
This paper presents the disturbance and uncertainty suppression by using the nonlinear disturbance observer and an extended state observer for a nonlinear active magnetic bearing system. Otherwise, the chattering free is assured by a fuzzy controller, where the fixed sliding mode surface boundary is regulated by fuzzy boundary layer. The stability of the system is guaranteed by Lyapunov condition. First, the nonlinear disturbance observer is presented to estimate the disturbance from outside of the system. Second, the system parameter variations are estimated by an extended state observer with the construction via the estimated disturbance value. Third, the proportional–integral–derivative sliding mode surface has been constructed due to the chattering values that appear from the high-frequency switching control values. Fourth, these chattering values are reduced by using a Mamdani fuzzy logic control. The proposed control methodology was given by the MATLAB simulation. The overshoot value that is equal to zero, narrow settling time, and the average distance tracking error value which is quite small are archived.
Highlights
Active magnetic bearing system (AMBS) has been applied in many areas in industrial system
The robust nonsingular terminal sliding mode control was applied to suspension AMBS.[4] the proposed method ignored the outside disturbance effects analysis, the method proposed by Su et al.[2] is very good but complicated in real practice, and the method proposed by Tsai et al.[3] is complicated to understand how much the lumped uncertainties are bounded
This paper proposes the disturbance and uncertainty rejection based on extended state observer and via the nonlinear disturbance observer (DOB), which means the disturbance needs to be defined first by an observer, and the system state estimation is constructed with estimated DOB and the error of estimated state and measured state through the extended state formulation
Summary
Active magnetic bearing system (AMBS) has been applied in many areas in industrial system. If the sliding mode surface is outside 1⁄2Àe, e, the fuzzy output needs logic with single input and single output, which is equipped to force the chattering value equivalent at the zero point; the fuzzy rules are as follows: If s(t) is negative big, uf(t) is positive big. The originality of this paper is the lump of uncertainty estimation; there, the extended state observer is built based on the observed disturbance value. In comparison with each methodology for AMBS, the proposed control methodology with a fuzzy logic control to regulate the sliding mode boundary layer thickness, disturbance, and uncertainty-based observers is performing good that the settling time is small, overshoot is approximated to zero, and distance tracking error values are quite small. This control methodology cannot guarantee the disturbance and uncertainty, and chattering will be rejected
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